<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="utf-8">
</head>
<body>
	<script>
	//check value is false
		var isTure=function(aValue){
			var temp;
			if(aValue){
				temp=true;
			}else{
				temp=false;
			}
			return temp;
		}
		console.log(isTure(null));
		console.log(isTure(undefined));
		console.log(isTure(NaN));
		console.log(isTure(""));
		console.log(isTure(0));
		console.log(isTure(false));
		console.log(isTure("1"));

	//check value is null
		var isNull=function(aValue){
			var temp;
			if(aValue===null){
				temp=true;
			}else{
				temp=false;
			}
			return temp;
		}
		console.log("check value is null")
		console.log(isNull(null));
		console.log(isNull(undefined));
		console.log(isNull(NaN));
		console.log(isNull(""));
		console.log(isNull(0));
		console.log(isNull(false));
		console.log(isNull("1"));
	//the other way of checking value is null
		var isNullOther=function(aValue){
			var temp;
			if (!aValue && typeof aValue != "undefined" && aValue!= 0&& typeof aValue=="object")
			{
				temp=true;
			}else{
				temp=false;
			}
			return temp;
		}
		console.log("the other way of checking value is null");
		console.log(isNullOther(null));
		console.log(isNullOther(undefined));
		console.log(isNullOther(NaN));
		console.log(isNullOther(""));
		console.log(isNullOther(0));
		console.log(isNullOther(false));
		console.log(isNullOther("1"));
	</script>
</body>
</html>